Study on coastal upwelling in eastern Hainan Island and western Guangdong in summer, 2006

In this paper, the hydrographic survey data in coastal waters of Guangdong, Hainan, and Guangxi during the summer of 2006, combined with QuikSCAT wind data were used to document spatial characteristics of upwelling, and to explore roles of the wind and wind stress curl on the upwelling, and responses of temperature, currents, sea level to the upwelling. The results show that the coastal upwelling regions in eastern Hainan and western Guangdong are not separated but merged together below 10 m layer. The coastal upwelling in eastern Hainan is mainly driven by the southwest monsoon during summer, and the wind stress curl also impacts the process of upwelling. The coastal upwelling in western Guangdong is mainly caused by the local wind stress curl. The intensity of upwelling in eastern Hainan coast was stronger than that in western Guangdong coast. In eastern Hainan coast, the water in upper layer (<18 m) moved primarily offshore, while the water in lower layer moved dominantly onshore, with a stronger flow in upper layer. The upwelling phenomenon in eastern Hainan is intermittent, and modulated by the strength of alongshore wind. The strength of coastal upwelling in eastern Hainan was closely correlated to local sea surface height, with variations of former lag that of later in 1-2 days.